Heat Transfer Modeling and CFD Simulation of Plate Type Heat Exchangers

ABSTRACT

For many industrial applications, Plate Heat Exchangers (PTHEs) are demonstrating superiority over other type of heat exchangers. Heat transfer modeling of these heat exchangers is complicated due to flow in narrow channels. In this paper, effectiveness-NTU method has been applied for evaluating heat transfer duty for given surface area of cross flow type PTHEs. Effectiveness-NTU method can be used for finding out heat transfer in single or multiple cross flow / counter flow arrangements of fluids. Various existing correlations of heat transfer coefficient have been investigated to find out their applicability for thermal design of a typical PTHE. Limitation and usefulness of these correlations with respect to PTHEs have been discussed. Many of Refinery's application of PTHEs require transferring heat from high temperature flue gases having high H₂O & CO₂ components. Method has been proposed to estimate radiative heat transfer from these components. It was found that correlations available in open literature gave overall heat transfer coefficient far lower than the design performance data of a typical PTHE. Finally, heat transfer investigation has been done using Computational Fluid Dynamics (CFD) technique, utilizing latest commercial software ANSYS Fluent. Modeling approach, mesh dependency study, simulation technique & applicable turbulent solver model have been described. CFD results matched very closely with design performance data of typical PTHE. Reasons of deviation in heat duty predicted by existing heat transfer correlations and CFD have been discussed.

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